A drawback of mixing together processing ingredients, for example a developer fluid with an activator, is the creation of an unstable processing solution. The unstable processing solution will have a tendency to deteriorate over a short period of time, thus will have to be flushed out of a photographic processing apparatus and discarded. This type of photographic processing apparatus is unattractive especially for a minilabs environment due to large amounts of effluent which have to be discarded.